Asthma Flashcards
what is a drug history used as part of?
Used as part of medicines reconciliation
what are the 3 types of inhalers?
pMDI, dry powder and breath actuated
what group of patients is a pMDI useful for?
Good for majority of patients, but tricky for elderly and children
what group of patients is a dry powder inhaler useful for?
useful for patients over 5 years
What group of patients is a breath actuated inhaler useful for?
Better for older children and adults
describe the inhaler technique
First test inhaler by: removing cap; check dose counter, and point inhaler away from you and press canister once. To use:shake inhaler, make sure you are sat/standing upright with chin slightly tilted upwards, breath out gently away from the inhaler until lungs feel empty, then place mouthpiece between lips to form tight seal and start to breath in slowly and steadily. At the same time, press the canister once and continue to breath in until lungs feel full. Remove inhaler, and with lips closed, hold breath for up to 10 seconds then breath out. when finished, replace the cap.
why should you slightly tilt chin up when using an inhaler?
This helps the medicine reach the lungs better
explain the neural control of ventilation
Peripheral chemoreceptors detect changes in pH, pCO2 and pO2. Impulses are sent to respiratory centre via sensory nerves.
What is the normal heart rate range?
Between 60-100bpm
describe the regulation of ventilation
Respiratory centre consists of inspiratory and expiratory groups of neurons. These are regulated by the pneumotaxic centre.
describe what occurs during inhalation
The diaphragm contracts (moves down)
describe what occurs during exhalation
the diaphragm relaxes (moves up)
What is the importance of immunology?
many drugs use the immune system to treat diseases (autoimmune, cancer, allergic contact dermatitis)
Give examples of drugs used in immunology
monoclonal antibodies, anticytokine therapies
define immunology
the discipline of medicine concerned with: structure and function of immune system, innate and acquired immunity, and bodily distinction of self
what is key in immunology?
Communication
Give examples of physical and chemical barriers in immunology
skin, sebum, tears and sweat (lysozyme in tears), GI, respiratory and genito-urinary tracts are lined with mucous membranes which secrete mucous to trap microbes, ciliated epithelia in GIT to trap microbes, saliva and urine wash away microbes
What are the primary lymphoid tissues?
Bone marrow (B cells), thymus (t cells), lymphocyte development and haematopoiesis
What does the lymphatic system consist of?
primary lymphoid tissues, secondary lymphoid tissues, tertiary lymphoid tissues
What are secondary lymphoid tissues?
spleen, lymph nodes, gut associated lymphoid tissue and peyers patches, tonsils
What occurs in secondary lymphoid tissues?
Site where lymphocytes congregate and adaptive immune responses are initaited
what does the thymus consist of?
Cortex and medulla
Describe the structure of the cortex
packed with immature thymocytes from bone marrow
describe the structure of the medulla
cellular ‘mesh’ which makes up the thymus called stroma and comprises t-lymphocytes
what are the 2 major roles of the thymus?
- secretion of growth factors to mature thymocytes- maturation to t helper and t cytotoxic cells
- exposure of thymocytes to self epitopes on stroma- t cells recognising self die via apoptosis
Describe the structure of the spleen
Highly vascular and composed of red and white pulp (lymphoid tissue) and periarterial sheath (mostly t cells), has a marginal zone (many b cell follicles)
What are lymph nodes?
Immunological filter allowing contact between antigen and immune cells
what are lymph nodes composed of?
cortex, paracortex and medulla
what does the cortex consist of in lymph nodes?
dendritic cells presenting antigen and B cell follicles, where B cells proliferate
what does the paracortex in lymph nodes consist of?
many t cells
what occurs in the medulla of lymph nodes?
area of B cell antibody secretion
where are lymph nodes located?
adjacent to GI and respiratory tracts
what does malt stand for?
Mucosa associated lymphoid tissue
what are mucosa associated lymphoid tissue?
diffuse system of small concentrations of lymphoid tissue found in submucosal membrane sites
What do MALT consist largely of?
consists largely of groupings of lymphoid follicles
Give examples of MALT
Tonsils, appendix, peyers patches
what is essential for an effective immune system?
Communication between cells
what are the types of cells present in the immune system?
granulocytes, mononuclear cells, macrophages, dendritic cells, natural killer cells and NKT cells
Give examples of granulocytes
neutrophils, eosinophils, basophils and mast cells
give examples of mononuclear cells
lymphocytes, monocytes
what are the 2 types of immune response?
innate and adaptive immunity
what are the characteristics of innate immunity?
inborn and non specific
what does adaptive immunity consist of?
memory, specificity, and includes cell mediated and antibody mediated responses
Give examples of cells involved in innate immunity
dendritic cells, mast cells, macrophages, basophils
Give examples of cells involved in adaptive immunity
B cells, t cells, antibodies
Give examples of cells involved in both innate and adaptive immunity
T cells, Natural killer T cells
What are neutrophils and what is their role?
predominant granulocyte cell (consists of 60% circulating cells)
first cells to arrive at site of infection and engulf and destroy infectious agents
what are eosinophils and what is their role?
Contain cytoplasmic granules (eg. major basic protein) and eosinophil perioxidase
important for parasitic infections
What are basophils and what is their role?
minor cell population, role largely unknown but thought to play role in allergy through histamine release
what are mast cells and what is their role?
contain histamine and cytokines, and generate eicosanoids which are key to allergic reactions
What are B lymphocytes and what is their role?
Develop in bone marrow and mature in spleen
prior to antigen exposure, they are not yet producing antibody (naive)
after exposure, they proliferate and develop into plasma cells, producing increased levels of antibodies
where are T lymphocytes developed?
In the thymus
What are monocytes and what is their role?
precursors of tissue macrophages and dendritic cells
infiltrate tissue at site of infection and eliminate debris
What is the role of macrophages?
phagocytose unwanted material and then present the antigen to T cells
What are dendritic cells and what is their role?
have long dendrites that can interact with many cells
highly efficient antigen presenting cells, derived from myeloid or lymphoid
what are natural killer cells and what is their role?
large lymphocyte lineage cells which kill other cells on contact.
kills tumour cells and some virus infected cells and recognise targets by low/no MHC I expression.
react against microbial antigens
what is involved in immune cell signalling?
lipid mediators, polypeptide factors and cytokines
Give examples of lipid mediators?
eicosanoids, prostaglandins and thromboxanes
what side effects do platelet activating factors have?
muscle contraction, sleep disturbances
give examples of polypeptide factors
cytokines, complement and acute phase proteins
how do cytokines act?
act via autocrine, paracrine or signalling
define antigen
immunogen or a hapten foreign to body that evokes an immune response, either alone or after forming complex with larger molecule
what are antigens capable of?
capable of binding with product (as an antibody or t cell) of the immune response
‘the on/off switch of the immune system’
define epitopes
parts of the antigen recognised by the immune response
what is the goodness of fit of an antigen to antibody important for?
important in determining strength of binding
What could occur if an epitope is a low affinity binder to an antibody?
its possible that the antibody could bind to another similar epitope- cross reactivity
describe the factors contributing to immunogenicity of antigens
size (higher than 1kDA otherwise haptens), difference from self, dose and class (carbohydrate, lipid, nucleic acid and proteins)
what are antibodies?
soluble proteins that bind to antigens, can exist as membrane form and function as a B cell receptor
what are idiotypes?
antibodies which vary in the variable region
what does the variable region occupy?
occupies about 110 amino acids
what are the classes of antibody in humans?
IgM, IgD, IgG, IgE, IgA
What can produce the 5 classes of antibody?
B lymphocytes can produce all 5, but 1 at a time
what is IgG?
most abundant immunoglobulin in serum and consists of 4 subtypes (isotypes)
what are isotypes?
antibodies which vary in the constant region
What are the functions of IgG?
Transplacental transfer, agglutination, activation of complement, antibody dependant cytotoxicity, neutralisation and opsonisation
what is IgM and where does it exist?
Exists in 2 forms
- on surface of B lymphocytes as a single IgG like molecule
- in the circulating plasma as a pentameric (5 IgG like molecules) form
What are the functions of IgM?
very good agglutinator of antigens, foetal protection and activation of complement
What is IgA and how does it exist?
exists as a monomer or dimer with a J chain
What are the functions of IgA?
Protects mucosa- only antibody that can be secreted in any quantity across mucosa. to do so, it requires ‘secretory piece’ which acts as a suicidal transporter
neonatal protection from enteric pathogens
what is IgE and what are the functions?
similar to IgG but longer
Major role in asthma and allergy, and protection against parasitic infections
What is IgD and what are the functions?
produced along with IgG and serves as a B cell receptor and marker
Activates basophils to release antimicrobial factors
Describe the recognition of antigen by lymphocytes
Antigen binds to BCR or TCR to allow lymphocytes to proliferate and recognise the same antigen
what receptors regulate mucus secretion?
Muscarinic receptors
What are muscarinic receptors involved in?
muscarinic receptors are G protein coupled and are involved in: bronchoconstriction and increase mucus secretion at the neuroeffector junction
What are the main type of muscarinic receptors in the airways?
M3
does sympathetic innervation occur in the airways?
No sympathetic innervation although there are B2 adrenergic receptors that respond to adrenaline
what does the autonomic nervous system consist of?
Parasympathetic and Sympathetic nervous system
what are the functions of the lower respiratory tract?
distribution of air to alveoli, cleanse, warm and moisten air, and in mucus production
What surrounds bronchioles?
bronchioles have bands of smooth muscle surrounding airways
what does transmission at neuromuscular junction occur between?
occurs between a motor neuron and voluntary muscle
Forms part of the somatic nervous system
how does transmission at neuromuscular junction occur?
somatic motor neuron releases Ach at neuromuscular junction. Net entry of Na+ through Ach receptor channel initiates a muscle action potential
How does the regulation of intracellular Ca- occur?
Through negative feedback
what does curare cause?
causes muscle paralysis
what is tubocurarine used for?
a skeletal muscle relaxant to secure muscle relaxation in surgical procedures without deep anesthesia
give an example of a long acting non depolarizing muscle relaxant
Pancuronium
Give an example of an intermediate acting non depolarizing muscle relaxant
Atracurium, vecuronium, rocuronium
Give an example of a short acting non depolarising muscle relaxants
Mivacuronium
What is the mechanism of action of non depolarising muscle relaxants
bind nicotinic Ach receptors and competitively block acetylcholine, preventing muscle contraction
they are competitive antagonists
How can the block of acetylcholine be overridden in non depolarising muscle relaxants?
By the addition of cholinesterase inhibitors, which increases the concentration of Ach in synapse
What is the main use of non depolarising muscle relaxants?
Mainly used as an adjunct in anaesthesia
What are depolarising neuromuscular blockers?
Eg. Suxemethonium- not overcome by anti-cholinesterases
What are the 2 types of therapy used as a treatment for asthma?
controllers/preventers taken daily on long term basis to keep asthma under control, and relievers (rescue medication) used as needed to reverse bronchoconstriction
What are short acting beta 2 antagonists?
SABA, reliever- step 1
e.g salbutamol
What are long acting beta 2 antagonists?
LABA, preventers- step 3
e.g salmeterol and formoterol
define bronchodilate
relax airway smooth muscle and increase airflow to the lungs
What is the mechanism of action of beta 2 antagonists?
stimulate B2 adrenoreceptors and relax smooth muscle by raising cyclic AMP levels
What are the functions of beta 2 antagonists?
decrease production of inflammatory mediators from immune cells and increase mucocilliary clearance
What are inhaled corticosteroids classed as?
Preventers
When are inhaled corticosteroids used?
if a patient has experienced an exacerbation in the past 2 years; uses short acting beta 2 agonist 3< times per week; experiences asthma symptoms 3< times per week; wake up at least 1 night per week with symptoms
Give an example of an inhaled corticosteroid
Beclomethasone, fluticasone
What are oral corticosteroids classed as?
preventers
When would an oral corticosteroid be used?
High dose used in an acute attack, and lowest dose for adequate control of patients who suffer severe persistant/continuous symptoms
Give an example of an oral corticosteroid
prednisolone
What are the 2 actions of corticosteroids?
Anti inflammatory- stop release and formation of inflammatory substances (leukotrienes, prostaglandins)
immunosuppressive- stops proliferation and infiltration of white blood cells into inflamed areas
Name some side effects of oral corticosteroids?
hyperglycaemia, gastric ulcers, osteoporosis, cataracts, glaucoma, and brusing
Name some side effects of inhaled corticosteroids
Oral candidiasis, dysphonia and reflex cough
What are the main side effects of corticosteroids?
CORTICOSTEROIDS: Cushings syndrome osteoporosis retardation of growth thin skin and easily bruising infections and immunosuppression cataracts and glaucoma odema suppression of hypothalamic pituitary adrenal axis thinning and ulceration of gastric mucosa emotional disturbance rise in bp increase in hair growth others like fetal abnormalities and hypokalaemia diabetes mellitus precipitation stria
Describe step 3 of treatment of asthma
LABA used in combination with inhaled corticosteroid (never alone)
eg. Seretide: salmeterol and fluticasone; Symbicort SMART: budesonide and formoterol
what is step 4 of treatment of asthma?
Add on therapy
Give examples of add on therapy used in step 4
Methylxanthines, leukotriene antagonists, cromoglycates
What are oral/IV methylxanthines classed as?
Reliever and preventer, depending on formulation
Give an example of an oral/IV methylxanthine and when it would be used?
Theophylline (oral) used in step 5 and aminophylline (IV) used for acute exacerbations of asthma
Why is it important to use the same brand of theophylline in asthma treatment?
due to differences in bioavailability
What are the clinical effects of oral/IV methylxanthines?
- bronchodilation by: inhibiting breakdown of cAMP, and acting as an antagonist at adenosine receptors
- increased muco-ciliary clearance
- antiinflammatory effects- inhibits eosinophils
- reduces histamine and IL release from mast cells
Describe the theapeutic range of methylxanthines and what this may cause?
narrow therapeutic range- can cause seizures and arrhythmias
What are leukotriene receptor antagonists classed as?
preventer
Give examples of leukotriene receptor antagonists
Zafirlukast and montelukast
What are the functions of leukotriene receptor antagonists?
oral therapy taken at night. Relax airways and reduce mucus secretion, and inhibit exercise/aspirin induced asthma
What are lipoxygenase 5 antagonists used for?
prevent production of leukotrienes (eg zilutin)
little used due to liver side effects
What are cromoglycate and Nedocromil classed as?
preventers
How is cromoglycate administered?
given by aerosol inhalation, nebules and powder
how is nedocromil administered?
by aerosol inhalation, as it has no direct effect on smooth muscle given prophylactically
What are the roles of cromoglycate and nedocromil?
reduce bronchila hyper reactivity, and effective in antigen induced, exercise induced and irritant induced asthma
What must be noted before giving cromoglycate and nedocromil?
children more likely to respond than adults, and must be given before exposure to allergen
what is step 5 of asthma treatment?
daily oral corticosteroids at lowest dose possible for shortest amount of time
what is omalizumab classed as?
preventer
what is omalizumab and how is it administered?
monoclonal antibodies, brand name= xolair, given as injection every 4 weeks
what is omalizumab used for?
used to treat moderate/severe persistant asthma in those whose symptoms are not well controlled with inhaled corticosteroids
what is the mechanism of action of omalizumab?
binds free IgE in the serum, forming trimers and hexamers
drug binds to IgE at the same site that high affinity IgE receptor binds, so, IgE bound to drug cant bind its receptor on mast cells and basophils
what is the elimination half life of omalizumab?
7 days
where is omalizumab metabolised/eliminated?
by liver
describe the acquisition of antigen
foreign antigen enters body through skin, respiratory and GIT. Cells will pick up antigen and transport it to peripheral lymphoid tissues where adaptive immune responses are initiated
describe how adaptive repsonses occur?
antigen has to be presented to lymphocytes in organised lymphoid tissue by antigen presenting cells
what must immature dendritic cells do in adaptive responses?
immature Dendritic cells cant activate t cells, so must encounter antigen first, digest antigen into small peptide fragments
give examples of antigen presenting cells
macrophage, dendritic cells, langerhans cell
describe the process of dendritic cell maturation
immature dendritic cells become mature dendritic cells with increased MHC II and other receptors on its surface
what are dendritic cells responsive to?
cytokines and chemokines
what are the 4 main subfamilies that chemokines are grouped into?
CXC, CC, CX3C and XC
What is the role of chemokines?
these proteins exert biological effects by interacting with G protein coupled receptors, that are selectively found on the surface of target cells
what is the major histocompatibility complex MHC?
set of cell surface proteins essential for acquired immune system to recognise foreign molecules in vertebrates, which determines histocompatibility
what is the main role of MHC?
to bind to antigens derived from pathogens and display them on cell surface for recognition by appropriate t cells
also deterimines compatibility of donors for organ transplants and susceptibility ro an autoimmune disease
What are the 3 types of MHC?
MHCI, MHCII, MHCIII
What are the MHC class I genes?
HLA-A, HLA-B, HLA-C
what are the MHC class II genes in humans?
HLA-DP, HLA-DQ, HLA-DR
What are the MHC class III genes?
C2, C4 and factor b
encodes TNF and complement factors
how does the cleft size differ in MHC I and II?
type I= 8-10 amino acids long
type II= 12-18 amino acids long
Where is class I MHC found and what is its role?
found on all cells (except RBCs and neurons), known as transplantation Ag
presents endogenous Ag and interacts with CD8 on t cells
where is class II MHC found and what does it present?
found only on antigen presenting cells, presents exogenous Ag
interacts with CD4 on t cells
describe how MHC is involved in organ transplant process
determines whether an organ transplant is rejected or accepted
organ rejection is normal, as the immune response is directed towards non self MHC molecules
describe the role of MHC
t cell only recognises antigen when its presented by an antigen presenting cell that has a particular MHC molecule- MHC restriction
applies to CD8 t cells recognising MHCI and CD4 recognising MHCII
Where is CD4 found?
found on t helper cells
where is CD8 found?
found on t-cytotoxic cells
what does the relationship between MHC and CD4/8 define?
the type of immunological reaction
describe an endogenous antigen immune response
(intracellular-virus, parasite, cancer marker)- MHC class I presentation, CD8 and TCR recognition, activation T cytotoxic cells, killing of infected cells
describe what occurs in an exogenous antigen immune response?
(extracellular- bacterium, parasite, extracellular virus phase)- MHC class II presentation, CD4 and TCR recognition, activation of T helper cells, cytokines released to help B cells produce antibody
what are the 2 major pathways where antigens are processed and presented to t cells?
exogenous- taken up from outside the cell and presented to MHC II
endogenous- made up inside the cell and presented to MHC I
what are naive cells?
those which are meeting antigen for the 1st time
what are effector cells?
those which have gone through Ag stimulation and become activated, proliferate and ready to kill target cells
what other accessory molecules are involved in t cell activation?
LFA1-ICAM1 are adhesion molecules, CD28 is a critical receptor for B7-1 and B7-2 before stimulation
after stimulation, CD28 becomes CTLA-4 which inhibits further reactivity
What cells are involved in innate immunity?
polymorphonuclear leukocytes (PMNs, polymorphs, neutrophils), effector cells with cytotoxic granules (perforin/granzymes), M1 (pro inflammatory) and M2 (anti inflammatory), capture debris (APC)
describe the characteristics of polymorphonuclear leukocytes
very aggressive, short lived cells with characteristic multilobed nucleus
describe the characteristics of effector cells
rapid innate immunity
describe the role of M1 and M2 cells
promote angiogenesis and favour tumour progression
describe the role of capture debris
activates naive t cells
what is the role of epithelia?
impose physical barrier between body and external milieu
what do epithelial surfaces comprise of?
comprise of skin and linings of bodys tubular structures, GI, respiratory and urogenital Tract
describe the structure of the skin
outer layers of epidermis consists of the stratum corneum, which consists of dead corneocytes, full of keratin, seperated by lipid layers (landmann units).
this creates waterproof and impermeable layer
what occurs if keratinocytes are damaged?
produce TNF and IL-8 which leads to inflammation
what occurs on mucosal surfaces?
mechanical protection via a layer of mucus
what are mucosal surfaces used for in the airway?
the mucociliary escalator moves mucus and trapped particles to the throat to swallow
what is the role of the mucosal surfaces in the stomach?
the mucus protects gastric mucosa from stomach acid and enzymes
what is the role of the mucosal surfaces in the uterine cervix
protects uterus from bacterial invasion
breach by old style IUD threads could lead to pelvic inflammatory disease
what is the role of mucosal surfaces on the eyes?
on the eyes corneal surface, it protects the corneal epithelium
what occurs when a virus makes it into a cell?
antibodies cant bind to them anymore to prevent its entry, so something must be able to recognise virally infected cells and eliminate it
give examples of the types of T cells
T helper cells, cytotoxic lymphocytes and t regulatory cells
what is the difference between t cells and b cells?
t cells can also recognise antigens, but unlike b cells, these antigens can only be protein fragments
describe how t cells work
t cell receptor recognises and binds simultaneously to the foreign protein fragment and to the self protein (MHC) on the surface of affector protein cells
what are pattern recognition molecules and what are they used for?
IMS is armed with pattern recognition receptors that recognise pathogen associated molecular patterns (PAMPs) not found in host, then activates immune response